The Theory of Exchange

Menger explains exchange without assuming equal value. Trade occurs because two people value the same goods differently. One person values a quantity of grain more than a horse; another values the horse more than that grain. If each gives up what is less important to obtain what is more important, both gain. Exchange is therefore not an equality of values but a double improvement in want-satisfaction.

Exchange is possible only within limits. A person will not give more than the importance of the good received, and will not accept less than the importance of the good surrendered. The bargaining range lies between the seller's minimum and the buyer's maximum. Within that range, the exact terms depend on bargaining, competition, information, and alternatives.

Exchange lets people improve the allocation of goods beyond what isolated economizing could achieve. If one person has more of a good than is important at the margin, while another has urgent uses for it, trade moves goods toward higher-valued uses. The result is not charity or arithmetic equality, but a better fit between goods and wants.

Chapter 4 can be read as an exchange map. Two actors rank goods differently. A trade is possible when each values what he receives more than what he gives. The bargaining range is bounded by those valuations. Competition and alternatives narrow the final terms. Exchange therefore creates mutual gain by moving goods into more valued uses.